Various devices have been used in the past to introduce a prescribed medicinal or other fluid from outside the body into subcutaneous tissue needing treatment. Injections with hypodermic needles have frequently been considered the standard means to be used for this purpose, but such injections normally cannot provide a supply of prescribed fluid in a manner to be continuously available over an extended period of time, without multiple injections and consequent puncture injuries to the body being treated.
Other means for feeding medicaments to the tissue supporting the skin are shown in the U.S. Pat. Nos. 3,814,097 to Ganderton et al, June 4, 1974 and 3,964,482 to Gerstel et al, June 22, 1976. The devices shown in these patents including skin pricking fingers or projections having a length to just pass through the skin but the projections do not pass into the subcutaneous flesh. These patents disclose applicators for feeding a drug or the like from a reservoir along or through a projection to permit a timed release of the drug under the skin but neither teaching can place the drug deeply into a subcutaneous area, for example, in the flesh between the peritoneum and the skin.
Another known time release drug applicator is shown in the two U.S. Pat. Nos. to Lee et al, 2,546,759, Mar. 27, 1951 and 2,625,158, Jan. 13, 1953, both of which show a vehicle for carrying an entire dosage of a medicine to be administered into a position under the skin for slow absorption in the body of the poultry product being treated. The dosage is positioned in an enlarged center of the device that is drawn under the skin for subcutaneous absorption. The treatment accomplished with this teaching distributes the medicine throughout the entire body of the animal and is not intended to provide nor can it normally produce a localized treatment of a given subcutaneous area.
More recently it has been proposed to feed fluids into the flesh through Teflon or stainless steel tubes having only a very limited degree of flexibility, such a procedure being shown in the U.S. Pat. No. 3,640,269 to Delgado, Feb. 8, 1972. The more or less rigid tubes shown are impervious to flow of fluid through their walls and it is necessary to attach a porous bag at the open end of the implanted tube to allow fluid to flow to or from the area of the flesh surrounding the implanted end of the tube. Such a structure allows only for a generally perpendicular insertion of a tube into a limited area of the subcutaneous flesh and would require many implantations if an extensive area were required to be treated.